FURFOOZ, a village some 10 m. from Dinant in the Ardennes, Belgium. Three caves containing prehistoric remains were here excavated in 1872. Of these the Trou de Frontal is the most famous. In it were found human skeletons with brachycephalic skulls, associated with animal bones, those of the reindeer being particularly plentiful. Among the skeletons was discovered an oval vase of pottery. The Furfooz type of mankind is believed to date from the close of the Quaternary age. G. de Mortillet dates the type in the Robenhausen epoch of the Neolithic period. His theory is that the bones are those of men of that period buried in what had been a cave-dwelling of the Madelenian epoch.
FURFURANE, or Furane, C4H4O, a colourless liquid boiling at 32° C., found in the distillation products of pine wood. It was first synthetically prepared by H. Limpricht (Ann., 1873, 165, p. 281) by distilling barium mucate with soda lime, pyromucic acid C4H3O·CO2H being formed, which, on further loss of carbon dioxide, yielded furfurane. A. Henniger (Ann. chim. phys., 1886 [2], 7, p. 220), by distilling erthyrite with formic acid, obtained a dihydrofurfurane
C4H6(OH)4 + 2H2CO2 = C4H6O + CO + CO2 + 4H2O,
which, on treatment with phosphorus pentachloride, yielded furfurane. Furfurane is insoluble in water and possesses a characteristic smell. It does not react with sodium or with phenylhydrazine, but yields dye-stuffs with isatin and phenanthrenequinone. It reacts violently with hydrochloric acid, producing a brown amorphous substance. Methyl and phenyl derivatives have been prepared by C. Paal (Ber., 1884, 17, p. 915). Paal prepared acetonyl acetophenone by condensing sodium acetoacetate with phenacylbromide, and this substance on dehydration yields αα′-phenylmethylfurfurane, the acetonyl acetophenone probably reacting in the tautomeric “enolic” form,
| CH3·CO·CHNa·COOR + C6H5·CO·CH2Br = CH3·CO·CH(CH2COC6H5)·COOR. |
This ester readily hydrolyses, and the acid formed yields acetonyl acetophenone (by loss of carbon dioxide), which then on dehydration yields the furfurane derivative, thus
L. Knorr (Ber., 1889, 22, p. 158) obtained diacetosuccinic ester by condensing sodium acetoacetate with iodine, and by dehydrating the ester he prepared αα′-dimethylfurfurane ββ′-dicarboxylic acid (carbopyrotritaric acid), which on distillation yields αα′-dimethylfurfurane as a liquid boiling at 94° C. Paal also obtained this compound by using monochloracetone in the place of phenacylbromide. By the distillation of mucic acid or isosaccharic acid, furfurane-α-carboxylic acid (pyromucic acid), C4H3O·CO2H, is obtained; it crystallizes in needles or leaflets, and melts at 134° C.
Furfurol (furol), C4H3O·CHO, is the aldehyde of pyromucic acid, and is formed on distilling bran, sugar, wood and most carbohydrates with dilute sulphuric acid, or by distilling the pentoses with hydrochloric acid. It is a colourless liquid which boils at 162° C., and is moderately soluble in water; it turns brown on exposure to air and has a characteristic aromatic smell. It shows all the usual properties of an aldehyde, forming a bisulphite compound, an oxime and a hydrazone; whilst it can be reduced to the corresponding furfuryl alcohol by means of sodium amalgam, and oxidized to pyromucic acid by means of silver oxide. It also shows all the condensation reactions of benzaldehyde (q.v.); condensing with aldehydes and ketones in the presence of caustic soda to form more complex aldehydes and ketones with unsaturated side chains, such as furfuracrolein, C4H3O·CH:CH·CHO, and furfuracetone, C4H3O·CH:CH·CO·CH3. With alcoholic potassium cyanide It changes to furoin, C4H3O·CHOH·CO·C4H3O, which can be oxidized to furil, C4H3O·CO·CO·C4H3O, whilst alcoholic potash converts it into furfuryl alcohol. With fatty acids and acid anhydrides it gives the “Perkin” reaction (see [Cinnamic Acid]). Furfurol is shown to have its aldehydic group in the a position, by conversion into furfurpropionic acid, C4H3O·CH2·CH2·CO2H, which on oxidation by bromine water and subsequent reduction of the oxidized product is converted into n-pimelic acid, HO2C(CH2)5CO2H. Furfurol in minute quantities can be detected by the red colour it forms with a solution of aniline acetate.